TORONTO, May 08, 2007 /PRNewswire-FirstCall/ -- MedImmune, Inc.
today announced positive results from a large prospective trial
conducted for prevention of respiratory syncytial virus (RSV). The
trial compared motavizumab, the investigational monoclonal antibody
(MAb) also known as Numax(R), with Synagis(R) (palivizumab), the
standard of care for preventing RSV hospitalization in high-risk
infants. In the Phase 3 study involving 6,635 pre-term infants at
high risk for RSV, with a primary endpoint of non- inferiority,
motavizumab demonstrated overall 26-percent fewer RSV
hospitalizations compared with Synagis (p<0.01 for
non-inferiority). Additionally, motavizumab demonstrated a
statistically significant 50 percent reduction in the incidence of
RSV-specific medically attended outpatient lower respiratory
infections (LRIs) (p<0.01) compared with Synagis. These findings
were presented today in a poster entitled, Phase 3 Trial of
Motavizumab, an Enhanced Potency RSV-Specific MAb for the
Prevention of Serious RSV Disease in High-Risk Infants, at the
Pediatric Academic Societies' Annual Meeting in Toronto,
Canada.

"As RSV continues to be the leading cause of lower respiratory
tract infections in infants in the United States, we are very
encouraged by the results of this Phase 3 trial, which suggest that
motavizumab may help to reduce the chance that our most vulnerable
babies will have serious RSV disease," said Edward M. Connor, M.D.,
chief medical officer and executive vice president. "Data from the
study showed that motavizumab was statistically superior to Synagis
for the secondary endpoint of outpatient medically attended LRI
caused by RSV, and thus may reduce the overall burden of RSV
disease compared to the current standard of care."

The Phase 3 study was designed to compare the safety and
efficacy of motavizumab with that of Synagis, which was first
launched by MedImmune in 1998, in reducing serious RSV disease in
high-risk infants in the inpatient and outpatient settings. As
defined in the study, infants who are at high risk for RSV include
those who were born at 35 weeks gestation or less as well as those
who have chronic lung disease (CLD) due to being born prematurely.
The primary endpoint was to assess the incidence of RSV
hospitalizations with motavizumab compared to Synagis. Motavizumab
met the primary endpoint, demonstrating non-inferiority to Synagis
with 26 percent fewer RSV hospitalizations in motavizumab-treated
infants. The overall RSV attack rate was low in both treatment
groups: 1.4 percent for infants who received motavizumab, compared
with 1.9 percent for those who received Synagis [RR: 0.740, 95
percent CI: (0.503, 1.083)]. The p-value for non-inferiority was
p<0.01, demonstrating a significant finding.

Analysis of the data also showed that motavizumab reduced the
incidence of RSV-specific medically attended outpatient LRIs (the
study's RSV-related secondary endpoint) by approximately 50 percent
compared with Synagis. The overall RSV-specific medically attended
LRI rate was 2.0 percent for infants who received motavizumab
compared with 3.9 percent for those who received Synagis
(p<0.01). There were no significant differences in other
non-RSV- specific endpoints.

"I am very pleased with the study results for motavizumab," said
Xavier Carbonell, M.D., Ph.D., lead study author, chairman of
neonatology, Barcelona Hospital Clinic, and vice president, Spanish
Neonatal Society. "As a practicing neonatologist, I look forward to
the potential to use this next- generation antibody to help reduce
RSV-related hospitalizations and LRIs in the outpatient
setting."

Data from this trial demonstrate that both study drugs were well
tolerated. The incidence and severity of adverse events (AEs) were
comparable for both treatment groups and were consistent with prior
experience with Synagis. There were comparable rates of related AEs
and drug discontinuations between treatment groups [related AEs:
motavizumab (N=298, 9.0 percent) vs. Synagis (N=258, 7.8 percent)
p=not significant (NS); discontinuations: motavizumab (N=13, 0.4
percent) vs. Synagis (N=10, 0.3 percent) p=NS]. AEs related to skin
hypersensitivity reactions resulted in discontinuation of dosing in
motavizumab-treated patients at low frequency (N=9, 0.3 percent).
In Synagis-treated patients, there were no AEs consistent with skin
hypersensitivity reactions that resulted in dosing discontinuation.
The overall mortality rates were not statistically different
between the two groups (N=8, 0.2 percent motavizumab and N=4, 0.1
percent Synagis); no death was considered to be related to the
study drugs and there were no RSV-related deaths. Immunogenicity in
the motavizumab arm was less than 1 percent and comparable to the
historical Synagis rate.

The trial was a randomized, double-blind study involving 6,635
high-risk infants at 347 centers in 24 countries through three RSV
seasons. Study participants comprised premature infants born at 35
weeks gestational age or less who were six months of age or younger
at randomization, as well as children with CLD related to
prematurity requiring medical management within the six months
prior to study entry, who were 24 months of age or less at
randomization.

About RSV

Each year, an estimated 125,000 infants in the U.S. are
hospitalized with severe RSV infections, the leading cause of lower
respiratory tract infections in infants in the United States. RSV
is the most common respiratory infection in infancy or childhood.
Approximately one-half of all infants are infected with RSV during
the first year of life, and nearly all children have been infected
at least once by the time they reach their second birthday.
Children born prematurely as well as those with CLD or congenital
heart disease (CHD) are at highest risk for severe disease and
hospitalization due to RSV. The virus may also cause severe illness
in other high-risk groups such as the elderly, those with
underlying respiratory or cardiac disease, and those with
compromised immune systems (e.g., bone marrow transplant
patients).

About Motavizumab

Motavizumab is an investigational humanized MAb being evaluated
for its potential to prevent serious lower respiratory tract
disease caused by RSV in pediatric patients at high risk of RSV
disease. Phase 1 and Phase 2 study data have been reported showing
that motavizumab appears to have a similar safety and
pharmacokinetic profile to Synagis in infants. Additionally, in
early phase studies children treated with motavizumab had reduced
RSV replication in the upper respiratory tract.

About Synagis

Synagis is the only MAb approved by the U.S. Food and Drug
Administration (FDA) to help prevent an infectious disease. Since
its licensure in 1998, Synagis has been administered to more than
1,000,000 infants in the U.S. and has become the standard of care
for infants at high risk for RSV. Synagis is indicated for the
prevention of serious lower respiratory tract disease caused by RSV
in pediatric patients at high risk of RSV disease, which is
prominent in the Northern Hemisphere during the winter months.
Synagis is a humanized MAb given by an intramuscular injection once
a month during the RSV season. Synagis was approved in 1998 by the
FDA; in 1999, by the European Medicines Evaluation Agency; and in
2002, by the Japanese Ministry of Health, Labor and Welfare. In
2003, the FDA expanded the U.S. label for Synagis for use in young
children with hemodynamically significant CHD at risk of RSV
disease. To date, Synagis has been approved in 62 countries,
including the United States. Synagis is indicated for the
prevention of serious lower respiratory tract disease caused by
respiratory syncytial virus (RSV) in pediatric patients at high
risk of RSV disease and is administered by intramuscular injection.
Safety and efficacy were established in infants with
bronchopulmonary dysplasia (BPD), infants with a history of
premature birth (less than or equal to 35 weeks gestation age), and
children with hemodynamically significant CHD. Synagis has been
used in more than one million children in the U.S. since its
introduction in 1998. The first dose of Synagis should be
administered prior to commencement of the RSV season. Patients,
including those who develop an RSV infection, should continue to
receive monthly doses throughout the season.

Very rare cases (<1 per 100,000 patients) of anaphylaxis and
rare (<1 per 1,000 patients) hypersensitivity reactions have
been reported with Synagis. Cases of anaphylaxis were reported
following re-exposure to Synagis and rare severe hypersensitivity
reactions occurred on initial exposure or re-exposure. If a severe
hypersensitivity reaction occurs, therapy with Synagis should be
permanently discontinued. If milder hypersensitivity reaction
occurs, caution should be used on re-administration of Synagis.

In clinical trials, the most common adverse events occurring at
least 1 percent more frequently in Synagis-treated patients than
controls were upper respiratory infection, otitis media, fever and
rhinitis. Cyanosis and arrhythmia were seen in children with
CHD.

MedImmune strives to provide better medicines to patients, new
medical options for physicians, rewarding careers to employees, and
increased value to shareholders. Dedicated to advancing science and
medicine to help people live better lives, the company is focused
on the areas of pediatric infectious diseases, cancer and
inflammatory diseases. With more than 2,500 employees worldwide,
MedImmune is headquartered in Maryland. For more information, visit
the company's website at www.medimmune.com.

Forward Looking Statements

This announcement may contain, in addition to historical
information, certain forward-looking statements regarding
motavizumab, an investigational MAb, which involve risks and
uncertainties. Such statements reflect management's current views
and are based on certain assumptions. Actual results could differ
materially from those currently anticipated as a result of a number
of factors, including risks and uncertainties discussed in
MedImmune's filings with the U.S. Securities and Exchange
Commission. The company is developing motavizumab for potential
future marketing. There can be no assurance that such development
efforts will succeed, that motavizumab will receive required
regulatory approval or that, even if such regulatory approval is
received, that motavizumab would ultimately achieve commercial
success.

Notice to Investors and Stockholders of MedImmune

This release is neither an offer to purchase nor a solicitation
of an offer to sell shares of MedImmune. MedImmune stockholders are
urged to read the relevant tender offer documents from AstraZeneca
PLC which have been filed on May 3, 2007 because they will contain
important information that stockholders should consider before
making any decision regarding tendering their shares. AstraZeneca
has filed tender offer materials with the U.S. Securities and
Exchange Commission, and MedImmune has also filed a
Solicitation/Recommendation Statement on Schedule 14D-9 with
respect to the offer. The tender offer materials (including an
Offer to Purchase, a related Letter of Transmittal and certain
other offer documents) and the Solicitation/Recommendation
Statement contain important information, which should be read
carefully before any decision is made with respect to the tender
offer. The Offer to Purchase, the related Letter of Transmittal and
certain other offer documents, as well as the
Solicitation/Recommendation Statement, are available for free at
the U.S. Securities and Exchange Commission's web site at
www.sec.gov, at
AstraZeneca's website at www.astrazeneca.com or at
MedImmune's website at www.medimmune.com.